A porcine 17kb genomic fragment was used as probe to map the lactase phlorizin hydrolase (LCT) gene to pig chromosome 15q13 by fluorescence in situ hybridization. Further, a three-allele TaqI RFLP was used to add the LCT gene to the proximal end of the chromosome 15 linkage map. Comparison of the human chromosome 2 gene map and the gene map of pig chromosome 15 indicates that the part of human chromosome 2 distal to the q13 band is homologous to pig chromosome 15.